JP4614764B2 - Water-soluble resin crosslinking agent - Google Patents

Description

  The present invention relates to an organic titanium having a hexacoordinate structure or an aqueous solution thereof, and particularly to a crosslinking agent for a water-soluble resin. Further, the organic titanium or an aqueous solution thereof is applied to a titanium oxide thin film forming agent, a photocatalyst precursor, an anchor coating agent, a coupling agent, a coating agent for paper and fibers, an inorganic binder for a rust preventive agent, ceramics. It can be used as a sintering agent.

Technical background

Titanium alkoxide reacts with a compound having a hydroxyl group, a carboxyl group or the like in the molecule as a crosslinking agent, and is therefore used as an adhesion improving agent, a coating crosslinking agent, a coating heat resistance improving agent, and the like. Further, it is widely used industrially as a catalyst for titanium oxide thin film production and esterification by the sol-gel method. However, since titanium alkoxide has very high hydrolyzability, insoluble matter is likely to be generated during operation and storage even by moisture in the air. Moreover, when using titanium alkoxide, it is necessary to use a large amount of an organic solvent, and the environmental load is extremely high. For this reason, a water-soluble titanium compound has been demanded as a titanium compound having a low environmental load and having hydrolysis resistance.
The water-soluble titanium compound technology currently on the market is a method in which a chelating agent is reacted with titanium alkoxide, which is titanium lactate or alkanolamine obtained by reacting hydroxycarboxylic acid lactic acid with titanium alkoxide. Examples thereof include titanium triethanolamate obtained by reacting triethanolamine and titanium alkoxide, and titanium oxalate obtained by reacting oxalic acid which is a dicarboxylic acid and titanium alkoxide. This is described in, for example, Patent Document 1 and Non-Patent Document 1. However, titanium lactate obtained by reacting lactic acid, which is a hydroxycarboxylic acid, and titanium alkoxide, tends to cause white precipitation during storage. In addition, titanium triethanolaminate obtained by reacting alkanolamine triethanolamine and titanium alkoxide is initially water-soluble, but when mixed with water and stored at 40 ° C, it becomes cloudy after one month. It loses fluidity and becomes a brown gel state. Furthermore, the latter titanium aminates are strongly colored and have a problem of limited use.
On the other hand, Patent Document 3 describes that a peroxotitanate compound having a specific ligand can provide a stable aqueous solution. However, since the compound has a peroxo group as a ligand, it tends to cause an oxidation reaction and its use may be limited.

JP 53-98393 A JP 2001-322815 A JP 2000-159786 A Sugiyama Iwayoshi, “Contained Metal Organic Compounds and Their Use”, M.M. R. Functional substance series No. 5, Japan, CMI Co., Ltd., March 18, 1983, p. 73-74 Inorganic Chemistry, 43, 15, 4546-4548, 2004 (Inorganic Chemistry, vol. 43 (15), 4546-4548, 2004)

Challenges to solve the problem

  The present invention relates to a water-soluble titanium compound or an aqueous solution thereof that can be mixed with water at an arbitrary ratio and does not cause turbidity or precipitation over a long period of time and has excellent stability, and a crosslinking agent for a water-soluble resin using the same. Is. Conventional water-soluble titanium has problems in the stability of aqueous solutions and their coloring. The present invention is easy to handle without being affected by moisture, can form a stable aqueous solution over time, and exhibits excellent performance when used for a thin film material containing a crosslinking agent or a titanium component. It is to provide a titanium compound that can be used.

Means to solve the problem

  The present inventors can mix with water at an arbitrary ratio, and do not cause turbidity or precipitation over a long period of time, and have excellent stability, or an aqueous solution thereof and a water-soluble resin crosslinked using the same. As a result of intensive studies on the method, it was found that organic titanium having a specific six-coordinate structure or an aqueous solution thereof is extremely stable over time and is extremely useful as a crosslinking agent. In particular, when an organic titanium coordinated with lactic acid or its derivative was used, it showed a high effect on the crosslinking of the water-soluble resin.

That is, the present invention provides (1) a water-soluble resin crosslinking agent comprising organic titanium represented by the formula (I) and having a six-coordinate structure or an aqueous solution thereof,

1

Ti [OCH (R) COOH] ₃ (I)
In the formula, R represents hydrogen or a methyl group. (2) The crosslinking agent according to (1) above, wherein the water-soluble resin is polyvinyl alcohol, polyamide, polyacrylic acid, polyacrylate, or a copolymer thereof.
Is to provide.

The invention's effect

The present invention provides a water-soluble titanium compound that can be mixed with water at an arbitrary ratio by using an organic titanium having a specific six-coordinate structure, and does not cause turbidity or precipitation over a long period of time. is there. Furthermore, the organotitanium compound of the present invention or an aqueous solution thereof is provided as a crosslinking agent capable of effectively crosslinking a water-soluble resin. Unlike the conventional organic titanium compounds, the organic titanium of the present invention is extremely stable in its aqueous solution, so that it is easy to handle when used, and is also useful as a titanium oxide thin film forming agent. Furthermore, the crosslinking reaction when polyvinyl alcohol is selected as the water-soluble resin can be more effectively carried out at a low temperature.
Moreover, since it is a water-soluble titanium compound, use and discharge | emission of an organic solvent can be reduced and the burden with respect to an operator and an environment can be reduced significantly.

BEST MODE FOR CARRYING OUT THE INVENTION

    The present invention is described in further detail below. The organotitanium having a six-coordinate structure of the present invention is represented by the formula (I).

2

Ti [OCH (R) COOH] ₃ (I)
In the formula, R represents hydrogen or a methyl group.

That is, when the organic titanium having a six-coordinate structure of the present invention is specifically exemplified, 3 mol of lactic acid molecules as described in Non-Patent Document 2 are chelate coordinated as bidentate ligands, Titanium metal has a six-coordinate structure. Such a structure is different from a generally known titanium compound chelated with lactic acid.
For example, product TC-310 of Matsumoto Pharmaceutical Co., Ltd. has a structure represented by the formula (II) and is inferior to the organic titanium of the present invention in terms of stability as an aqueous solution and performance as a crosslinking agent.

(HO) ₂ Ti [OCH (CH ₃ ) COOH] ₂ (II)

The organotitanium of the present invention is a complex in which a hydroxycarboxylic acid represented by the formula (I) and R is hydrogen or a methyl group is coordinated by 3 moles. In this case, the hydroxycarboxylic acid that is coordinated with the chelate does not need to be a common ligand of 3 moles, and any amount can be taken as long as the total amount is 3 moles per mole of titanium. For example, the organotitanium of the present invention also includes a complex in which R is a total of 3 moles of hydrogen and a methyl hydroxycarboxylic acid.
The organic titanium of the present invention can be obtained, for example, by dissolving about 3 times moles of lactic acid with respect to titanium in a titanium peroxy solution dissolved by reacting hydrogen peroxide with metal titanium powder and heating and drying the solution. it can. However, as long as the organotitanium of the present invention is represented by (I) and has a 6-coordinate structure, the effect is not changed even if it is produced by any method.
Further, when the organic titanium of the present invention is used, it may be a powder or an aqueous solution having an appropriate concentration, but it is preferably used as an aqueous solution.
In addition, even if other titanium components or other components are used together if necessary, they are included in the present invention as long as the essential effects are not lost.

The organic titanium of the present invention easily dissolves in water to provide a stable aqueous solution.
This aqueous solution can also be used as a cross-linking agent for water-soluble resins and optionally a titanium oxide thin film forming agent.
The water-soluble resin can be crosslinked using the aqueous solution of the present invention. Examples of water-soluble resins in which cross-linking occurs effectively include polyvinyl alcohol, polyamide, polyacrylic acid or salts thereof. Polymers having hydroxyl groups in the resin, such as copolymers having polyvinyl alcohol or vinyl alcohol units, cellulose-based resins Polyester resins and the like show preferred embodiments.
In particular, polyvinyl alcohol and copolymers thereof have a high crosslinking effect, and the titanium lactate of the present invention acts as an effective crosslinking agent.
Examples of the polyvinyl alcohol resin include fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, and silanol-modified polyvinyl alcohol.
The copolymer containing a vinyl alcohol unit is produced by copolymerizing an olefin such as ethylene and vinyl acetate and then saponifying, for example, saponified ethylene vinyl acetate copolymer.
Examples of the cellulose resin include methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose and the like.
The forms of these water-based resins include so-called water-soluble resins dissolved in water or water-containing solvents, resins dispersed in water such as emulsions and dispersions, resins in these forms and resins having no hydroxyl group Even when two or more are mixed, the crosslinking effect is exhibited. For example, it is useful even in a state where a resin having a hydroxyl group and a resin not having a hydroxyl group are mixed, such as a vinyl acetate emulsion or an acrylic emulsion using polyvinyl alcohol as a protective colloid.

The crosslinking method will be described using polyvinyl alcohol as an example.
When used as a crosslinking agent for a water-soluble resin, the molar ratio of titanium to the functional group of the resin is preferably 66: 1, although it varies depending on the type of resin.

When used as a thin film forming agent, the titanium compound of the present invention can be formed by dissolving or dispersing the titanium compound alone or in an appropriate solvent containing water.
In the case of using an aqueous solution, the thin film can be formed by a usual method, that is, by dipping or coating, but at that time, an appropriate additive can be coexisted for adjusting the viscosity or adding another function.

  Hereinafter, the present invention will be described in more detail with reference to examples.

  Although the manufacturing method of the organic titanium of this invention is illustrated below, as long as the structure of the organic titanium obtained is the same as this invention, it is not limited to the method of this example.

Organic Titanium Production Example After weighing 0.48 g of metal titanium powder in a 300 ml beaker, 40 g of 30% hydrogen peroxide and 10 g of 30% ammonia water were added while cooling with water. Since the titanium powder dissolves with heat generation, the cooling of the beaker is continued. After confirming that titanium was dissolved, 2.7 g of lactic acid was added and mixed. This reaction mixture was heated on a hot plate at 80 ° C. to evaporate water and the like, thereby obtaining powdery organic titanium.
X-ray diffraction revealed that the obtained organic titanium had a structure in which 3 moles of lactic acid was 6-coordinated in a chelate manner to the titanium atom.
Distilled water was again added to the obtained organic titanium powder to obtain an organic titanium aqueous solution.

Example 1 and Comparative Example 1

An aqueous solution of polyvinyl alcohol was prepared by the following method, and the insolubilization rate was measured in order to examine the crosslinking performance with the titanium compound.
A higher insolubilization rate indicates a higher degree of crosslinking.
Preparation of aqueous polyvinyl alcohol solution A 5% aqueous solution was prepared using "GOHSENOL" N-300 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) as the polyvinyl alcohol.

(1) Film formation method A predetermined amount of a titanium aqueous solution was added to and mixed with 100 parts by weight of a 5% polyvinyl alcohol aqueous solution. Thereafter, about 10 g was measured in a polypropylene cup having a diameter of 10 cm and dried at 105 ° C. for 2 hours or at 40 ° C. for 16 hours to obtain a uniform film.

(2) Evaluation method
Measurement of insolubilization rate : Put a film formed in a 100 mL beaker and about 50 mL of water, boil for 1 hour, and filter off insolubles using filter paper at room temperature. Then, it dries at 105 degreeC for 2 hours, and measures the mass of a filter paper and an insoluble part.
Insolubilization rate (%) = [(c−b) / a] × 100
Where a = mass of the film before the test (g)
b = mass of filter paper (g)
c = mass of filter paper + insoluble matter (g)

  Although the insolubilization rate by the existing titanium lactate (Matsumoto Pharmaceutical Co., Ltd. product: TC-310) whose composition was similar to the organic titanium of this invention was shown in Table 1, compared with a comparative example, in 40 degreeC of the low temperature side. It can be seen that the insolubilization rate is high. That is, the titanium compound having a specific structure of the present invention effectively exhibits a crosslinking effect.

Example 2 and Comparative Example 2

A saponified ethylene vinyl acetate copolymer (manufactured by Nippon Synthetic Chemical Industry Co., Ltd .: Soarnol 16DX) was diluted to 5% with a one-to-one solution of water / n-propyl alcohol, and 100 g of this was prepared in Example 1. After adding 2.8 g of an aqueous titanium solution (titanium content: 3.0%), the insolubilization rate was measured after film formation in the same manner as in Example 1. The insolubilization rate was measured by putting the film after film formation into a flask, adding a one-to-one solution of water / i-propyl alcohol, heating in a 90 ° C. bath, and measuring the insolubilization rate in the same manner as polyvinyl alcohol. Table 1 shows the insolubilization rate of the organic titanium of the present invention and existing titanium lactate (manufactured by Matsumoto Pharmaceutical Co., Ltd .: TC-310).

The organic titanium aqueous solution prepared in the production example was dropped onto a sufficiently washed alkali-free glass substrate and coated with a spin coater. The spin coater was performed at 2000 rpm for 20 seconds. The coated glass plate was air-dried and then fired at 550 ° C. for 1 hour. In order to investigate the effect of the photocatalyst on the glass plate, a fading test of an organic dye was performed. An aqueous solution of methylene blue having a concentration of 10 mg / L was prepared, and this was coated on the glass plate with 0.1 ml of a polyethylene film. The ultraviolet rays were black light 20 W and ultraviolet illuminance 1.0 mW / cm ² . For comparison, an unpainted glass plate was used. The methylene blue colored on the glass plate coated with the organic titanium aqueous solution prepared in the production example clearly showed fading, but the uncoated glass plate used as a comparison did not show significant fading.

The organic titanium and the aqueous solution of the present invention have excellent long-term stability, workability, reactivity, and are water-soluble, so that the amount of organic solvent discharged can be reduced, and the crosslinking of water-soluble resins with very little environmental impact Useful as an agent.

Claims (2)

A crosslinking agent for a water-soluble resin represented by formula (I) and comprising an organic titanium having a six-coordinate structure or an aqueous solution thereof.

In the formula, R represents a methylation group The water- soluble resin crosslinking agent according to claim 1, wherein the water- soluble resin is polyvinyl alcohol, polyamide, polyacrylic acid, polyacrylate, or a copolymer thereof.